How (In)Accurate Are Calorie Counters at the Gym?

After 30 minutes of sweating on the elliptical, you look down at the console (326 calories burned—not bad!) and start feeling pretty triumphant about your cardio session. After all, you just torched off the calories in the turkey sandwich you had for lunch! Or did you? We went to the experts to find out just how accurate your calorie readout really is. Read on to see which machines you can trust, plus tips on how to maximize your burn.

Elliptical

Why pound your joints on the treadmill when you can burn just as many calories getting in the elliptical groove while you watch Real Housewives? Here's why: A recent study named the elliptical trainer the least accurate when it comes to calorie counting, with most machines overestimating your burn by 42 percent, says Jay Cardiello, SHAPE fitness editor-at-large and founder of the JCORE Accelerated Body Transformation System.

Why are elliptical machines so off base? Unlike treadmills, which can closely replicate your normal gait, the movement of the elliptical is not a natural motion, Cardiello says. Ellipticals also vary from manufacturer to manufacturer in terms of the range of motion, so a 'standard' just is not feasible. Plus, while using the arm levers (handles) will increase your heart rate, your arms don't weigh a lot compared to your hips, butt, and leg muscles, says Michele Olson, Ph.D., professor of exercise physiology at Auburn University. "So don't confuse a pronounced increase in heart rate from more arm movement to mean a pronounced increase in calories expended."

Boost your burn: If you really want to maximize your calorie burn, try not to rely on this machine too often. The elliptical works well in cross-training cardio circuits because you spend a shorter amount of time on it (as sort of a recovery break in between two higher-intensity machines such as the treadmill and the stair mill, for example). If you can't bare the thought of stepping on a treadmill, use this ramped up routine to get the most out of your time on the elliptical.

Stair Stepper

Hang out at a gym long enough, and you'll notice a trend among most stair-stepper users: They lean over the console while taking super-short, quick strides instead of using their full range of motion. What's so bad about that? Leaning forward can decrease your total calorie burn by as much as 50 percent, Olson says. And even if you make it through your session without looking like a hunchback, most stair steppers still overestimate your total burn by about 20 percent, she adds.

Here's why: "Many models calculate the 'gross energy expenditure' and not the 'net energy expenditure.' Gross energy expenditure includes your resting metabolic rate, or the calories you would burn anyway," Olson says. "What you really need to know is how many more calories above your resting metabolic rate you are burning." So if the machine reads 400 calories burned, a 20-percent adjustment to find your net number reveals that the stair stepper workout is responsible for 320 of those 400 calories. "In other words, the workout caused you to burn 320 calories, and you would have burned the additional 80 sitting and reading a book anyway."

Boost your burn: Always stand up straight and only hold onto the handrails lightly (if necessary). If your gym has a stepmill—the machine with the big moving staircase—try using it instead of a stair-climber or stepper, which only require your legs to make small movements. It isn’t easy (there’s a reason a stepmill is always open when all the treadmills are taken!), but it’s worth the sweat.

Good news for treadmill fans: Experts agree that the calorie counter is pretty accurate, especially if you input your weight and don't use the handrails. The problem is that many treadmills don't ask for your weight and use a reference of about 155 lbs, Olson says. That means if you weigh 135 lbs, you're really burning about 15 percent fewer calories than the machine says (300 calories vs. 255 calories, for example).

Relying on the handrails—especially during higher inclines or while running at high speeds—can throw off your reading by as much as 40 percent (that 300 calories burned just became 180). And we're not just talking about the people who pull themselves up a hill for 20 minutes. Placing even just a slight amount of weight on the support rails can decrease the actual calories burned by 20 percent (or more), Olson says.

Boost your burn: To maximize your treadmill time, avoid the handrails and be sure to practice good posture. "Slumping over can have a major impact on your oxygen intake, making your workout harder," Cardiello says.

If you can, take your run outdoors whenever possible. "Running outdoors is more difficult on the body. And you can't equally compare the distance and speed with your treadmill run vs. outdoor running; the calibration and physical stress is less from the treadmill than your outdoor trail run."

Can't make it outside? Go a little longer (or farther) with your indoor session to make up for the terrain difference, or try this fat-blasting interval routine.

Stationary Bike

Stationary bikes are in their own class of cardio machines because they support your body weight, Olson says. "If the bike is calculating calories based on technical data such as METs (metabolic equivalents) and watts (which measures power output), the calorie readout can be very accurate." In fact, researchers at the University of California at San Francisco's Human Performance Center found stationary bikes to be the most accurate of all cardio machines, with an overestimation of only seven percent.

One thing to keep in mind: A bike can't determine your pedaling technique, which could throw off your final count, Olson says. "For example, you will burn more calories if you are using a standing climb posture at a heavy resistance, compared to seated pedaling at the same resistance. This is because when you stand and climb, you are no longer weight supported." How big is the difference? According to Olson, a 15-minute standing climb burns about 15 percent more calories than seated pedaling at the same resistance.

Take your calories-burned readout with a grain of salt. Too many machines ignore important factors such as your weight, use of handrails, or fitness level, which makes a big difference, Cardiello says. "[An individual's fitness level] is the biggest factor. How can a 200-lb, out-of-shape man and a 165-lb male considered to be in excellent physical condition burn the same amount of calories? They don't!"

Instead of relying solely on calorie counts, try monitoring your heart rate during cardio sessions or gauge your efforts using perceived rate of exertion. The "talk test" makes it easy to determine if you're really working hard (if you're gasping for air while trying to sing the lyrics of a song, you are at a near maximum intensity, Cardiello says).